1. Field of the Invention
The present invention relates to an edger rolling mill preferably disposed in a universal rolling facility for use to hot-roll a shape, such as an H-shape having a web and flanges, and formed by combining a universal rolling mill and an edger rolling mill.
2. Description of the Related Art
In general, when a shape, such as an H-shape having a web and flanges, is manufactured by continuous rolling, a raw material to be rolled to manufacture the shape, such as a bloom or a beam blank, has been rolled by a universal rolling facility which combines a universal rolling mill and an edger rolling mill. In this case, the edger rolling mill acts to roll the flanges of the H-shape to bring the flange width of the H-shape to a predetermined dimension. There is known in the prior art a type of the edger rolling mill which comprises a housing formed independently from the housing for the universal rolling mill and which has kaliber-type edging rolls for collectively restricting the web surfaces, the inside surfaces of the flanges and the end surfaces of the flanges of the raw material to be rolled.
There is known an attached-edger type rolling mill in Japanese Patent Laid-Open No. 63-303604. It has an arrangement wherein drum-type edger rolls are included in the housing of a universal rolling mill to restrict only the end surfaces of the flanges of a raw material to be rolled.
However, an edging rolling mill of the foregoing conventional type has a problem which will be discribed by making reference to the accompanying drawings.
Usually, the H-shape is manufactured in such a manner that a raw material to be rolled, such as a slab 71 or bloom 72 or a beam blank 73 obtained by continuous casting as shown in FIGS. 6A, 6B and 6C, is inserted into a heating furnace 80 shown in FIG. 7A so as to be heated to a predetermined level. Then, it is rolled to a rough form having a web and flanges by a rough rolling mill 81. A rough universal rolling mill 82 and an edger rolling mill 83 are used to reverse-roll the rough steel member several times. As an alternative to this, two roughing universal rolling mills 83 are disposed as shown in FIG. 7B and an edger rolling mill 83 is disposed between the two roughing universal rolling mills 82 to perform reverse rolling. As a result, the thicknesses of the web and flange portions of the raw material are gradually decreased as shown in FIGS. 8A and 8B so that the desired dimensions of the H-shape are realized. Then, a finish universal mill 84 is used to manufacture a final product as shown in FIG. 8C.
However, there has been a trend for the H-shapes for use in building or civil engineering to have various flange thicknesses and web thicknesses even if they have the same outer dimensions (constant web height and flange width) for efficiency in operation and economical advantage. If the foregoing edger rolling mill having the kaliber-type edging roll is used to perform edging-rolling in the aforesaid case, the size of the H-shape is fixed. Therefore, there arises a necessity when rolling H-shapes with fixed web heights How and flange widths Hf by the same rolling line by varying the web thickness tw and flange thickness tf shown in FIG. 9 to change the rolling rolls. This causes a problem in that a long time and much work is needed and the manufacturing yield considerably deteriorates because the rolling line must be stopped.
Since a body portion 91 of a kaliber-type edging roll 90 comes in contact with the flange portion hf and web portion hw of raw material h for manufacturing an H-shape as shown in FIG. 10, the peripheral speed of roll varies in corresponding regions. Therefore, a problem arises in that the raw material h has scratches on the surface thereof and another problem is that the rolls become worn in an excessively short time.
When the edges of an H-shape are rolled by using the drum-type edging roll disclosed in Japanese Patent Laid-Open No. 63-303604, edging rolling adaptable to the size of the shape to be rolled can be performed only by changing the interval of opening of the rolls even if the flange width is changed. However, the foregoing method has a structure wherein only the end surfaces of the flanges of the raw material are restricted, with the result that 10 guiding of the raw material to be rolled becomes unstable. In this case, there is a risk that the dimension (called a "flange depth" 1 shown in FIG. 9) from the web surface of the raw material to be rolled to the leading ends of the flanges of the same becomes different. What is worse, the risk of inclination of the flanges deteriorates the dimension accuracy.
As a result of research made to overcome the foregoing various problems experienced with the conventional technology for rolling shapes, there has been developed technology for manufacturing an H-shape with fixed outer dimensions, such as the fixed web height and flange width, by adjusting the inner dimensions of the web and the flange depth of the flange.
The foregoing technology is technology for rolling a shape by using an edging roll for rolling a shape and it is disclosed in Japanese Patent Laid-Open No. 62-77107, Japanese Patent Laid-Open No. 63-60008, Japanese Patent Laid-Open No. 63-199001, Japanese Patent Laid-Open No. 63-260610, Japanese Patent Laid-Open No. 3-275202, Japanese Patent Laid-Open No. 3-281003, Japanese Patent Laid-Open No. 4-4908, Japanese Patent Laid-Open No. 4-4909, Japanese Patent Laid-Open No. 5-15909, Japanese Patent Laid-Open No. 5-23713 and Japanese Patent Laid-Open No. 5-76912. In this prior art, an H-shape is rolled in such a manner that the end surfaces of the flanges of the raw material to be rolled are rolled by using the flange rolling rolls separately disposed on the main shaft in a state where the web and two-side corners of the flanges of the raw material to be rolled are restricted by using web-restricting rollers divided into two sections. The web-restricting rollers or the flange rolling rolls are disposed eccentrically from the axis of rotation of the main shaft. Furthermore, the pair of web-restricting rollers are vertically moved in a range of degree of the eccentricity so that height from the flange rolling rolls to the web-restricting rollers (that is, the height of the web-restricting rollers) is adjusted so as to be adaptable to the change in the flange depth of the H-shape. In addition, the divided web-restricting rollers and the flange rolling rolls are made to be movable mutually in the axial direction of the main shaft in order to adjust the roll interval between the rolls. As a result, the rolling process can be carried out in a manner dependent on change in the inner dimensions of the web.
The foregoing method is able to freely change the web thickness, flange thickness, flange width and the web height and the like. Size-free capability is realized. As a result, it aims to efficiently produce shapes having satisfactory functions and exhibiting excellent quality.
However, each of the structures disclosed in Japanese Patent Laid-Open No. 62-77107, Japanese Patent Laid-Open No. 63-60008, Japanese Patent Laid-Open No. 63-199001, Japanese Patent Laid-Open No. 63-260610, Japanese Patent Laid-Open No. 3-275202, Japanese Patent Laid-Open No. 3281003 and Japanese Patent Laid-Open No. 5-15909 involves an apparatus for rotating eccentric rings disposed between the two eccentric rings. Therefore, the two eccentric rings cannot be brought closer and, accordingly, the minimum distance between the web-restricting rings cannot be shortened satisfactorily.
Each of the structures disclosed in Japanese Patent Laid-Open No. 4-4908 and Japanese Patent Laid-Open No. 5-23713 employs a method of driving web-restricting rolls. Therefore, each encounters a problem that biting of the raw material by the edger rolling mill causes the web, which is intended not to be rolled, to be rolled undesirably.
Since the structure disclosed in Japanese Patent Laid-Open No. 4-4909 involves an arrangement wherein the right and left flange rolling rolls are rotated by individual drive sources, it is difficult to synchronize the two flange rolling rolls with each other and to positively transmit the rolling torque to the raw material.
Japanese Patent Laid-Open No. 5-76912 has a problem that an on-line adjustment cannot be performed.
The suggested edging roll for rolling a shape has a problem in that the inside bulging portions of bulgings B formed on both inside and the outside of the leading portion of the flange hf of H-shape h, during the rolling operation, comes in contact with the web-restricting roller 8 which is being rotated as shown in FIG. 11 and therefore it is cut (as represented by hatched section Bb shown in FIG. 11) and causes undesirable flying dust. Furthermore, the web-restricting roller 8 does not support the leading portion of the flange hf. Therefore, there is another unsolved problem in that the restricting force of the leading portion is too weak to prevent deterioration in the dimension accuracy, such as inclination of the flange.
Although the structures disclosed in Japanese Patent Laid-Open No. 63-60008, Japanese Patent Laid-Open No. 63-199001 and Japanese Patent Laid-Open No. 63-260610 have suggested an apparatus for eliminating the clearance on the inside of the flange, a problem arises in that the structure is too complicated.
Some of the suggested edging rolls for rolling a shape have an arrangement wherein both web-restricting rollers and flange rolling rolls are operated synchronously. If the height setting for the web-restricting rollers is adjusted to adjust the flange depth, the roll width between the web-restricting rollers is changed in synchronization with the adjustment. Therefore, the roll width must be corrected individually when the roller height is adjusted, causing the process to become too complicated. Furthermore, power for driving the roll-width adjustment portion is required in addition to the power for driving the roller-height adjusting portion. Therefore, there arises a problem of greater energy consumption required to drive the apparatus.